What problems were the American’s facing in the 5th year of the revolutionary war?

In the first years of the Revolutionary War, George Washington and his Continental Army faced a threat that proved deadlier than the British: a smallpox epidemic, lasting from 1775-1782. Infrequent outbreaks and wariness of inoculation made his troops very susceptible to the disease.  After heavy losses in Boston and Quebec, Washington implemented the first mass immunization policy in American history.  

hello there the answer is a

sorry if i am wrong hope that : )

i am sure the answer is d